This invention relates to improvements in heating devices, and, more particularly, to portable heaters used to maintain ice fishing holes open and provide auxiliary heating for comfort and cooking in frigid temperatures on the ice.
It is well known that in the sport ice fishing extremely cold weather conditions affect the comfort and patience of a fisherman. One of the most troublesome problems experienced is that once a hole has been bored in the ice surface to gain access to the lake, stream or river water below, it is very difficult to prevent refreezing of water within the hole. Once this happens, the fishing line and bobber eventually become frozen in the ice and the fisherman's ability in determining if bait is taken and in retrieving a hooked fish are definitely impaired. Rather than chopping and straining the ice repeatedly at a hole, it has been found desirable to develop various heating devices for maintaining the openness of the hole.
One group of prior art devices directed to solving the above problems, include heaters having housings adapted to be supported on the ice completely surrounding the hole such as shown in U.S. Pat. Nos. 3,507,268 to Anderson and 4,006,732 to Schumm. Other structures are provided with housings which depend from the ice into or above the hole as illustrated in U.S. Pat. Nos. 2,541,328 to Boklep, 2,990,829 to McDonough et al, and 4,294,030 to Stewart. All of these heaters use charcoal, propane gas or some type of liquid fuel to radiate heat around the hole so that refreezing will not occur.
Another species of heater is shown in U.S. Pat. No. 4,612,910 wherein a housing having a heat source is buoyantly supported in the hole. Deflecting means disperse heat from the center of the heater towards the walls of the hole.
Still another prior art device is shown in U.S. Pat. No. 3,545,118 to Stelmach which sets forth ice fishing equipment including a heater adapted to be placed adjacent one side of the hole. The heater directs heat downwardly to a portion of ice at one side of the hole, thereby melting the ice and feeding water to the hole.
Various attempts have been made by each of these patents to alleviate the reformation of ice within the hole. However, such structures remain complex and cumbersome, require high manufacturing costs, produce insufficient or dispersed heat levels, cause burning and/or tangling of the fishing line and exhibit varying degrees of stability when mounted in place.
Thus, there remains a well defined need in this art for a simple yet novel self-contained, portable structure which produces efficient heat transfer, such as by vaporized heat, to maintain the open water in the hole.
While unrelated to the extreme cold weather problems discussed above, U.S. Pat. No. 3,424,547 to Winniett discloses a unitary, plug-in vessel used to produce vaporized heat for sterilization and food heating purposes in the home.
Accordingly, it is a principal object of the invention to provide an improved self-contained, portable heating device to be used at an ice fishing site to prevent formation of ice within a hole cut in the ice.
Another object of the invention is to furnish a heating device which offers an auxiliary heating feature for comfort and cooking.
It is a further object of the invention to provide a heater positioned away from the hole so as not to obstruct fishing and yet produce efficient delivery of heat to the hole.
A still further object of the invention is to provide a sturdy yet lightweight, easily manufacturable heater which is convertible to various heating applications.
One of the salient features of the invention is a retractable heater core which may be rearranged depending on the heating purpose.
An attendant feature of the invention is a guide rod structure used to position internal components of the heater and provide a support for objects placed thereon.
A further feature of the invention resides in the mounting of the fuel source and the combustion control of the fuel source provided by a damping structure on the housing.